Reciprocating slat-type conveyors (also referred to as, “RSCs,” “conveyor systems,” “live floor conveyors,” “reciprocating slat conveyors,” or “conveyors”) generally include a plurality of elongated slats (also referred to as “conveyor slats,” “floor slats,” or “deck slats”). The conveyors are generally used in the load-holding compartment of load transport vehicles (e.g. a mobile cargo trailer, bed of a truck (truck bed), rear portion of a semi-trailer, or container portion of a van-truck). The slats are arranged side-by-side to form the floor of the load-holding compartment so that they extend longitudinally to the framework of the load-holding compartment. A “load” may be, for example, grain, fertilizer, soil, sand, shredded documents, chipped wood, sawdust, garbage, or any particulate matter. The slats are generally grouped such that one group of slats (a group generally includes at least three slats although it is to be understood that each group may include any desired number in excess of two) moves simultaneously in one direction (the “load-conveying direction”) and then returns one slat at a time (in the “retraction direction”) to the beginning position. This operation results in a step-wise advance of the load positioned on the floor followed by a retraction of the slats without moving the load. Reciprocating slat-type conveyors are described in more detail in patents and patent applications assigned to and owned by applicant including, but not limited to, U.S. Pat. No. 8,125,478 entitled Adaptable Reciprocating Slat Conveyor, U.S. Pat. No. 8,430,231 entitled Adaptable Reciprocating Slat Conveyor, U.S. Pat. No. 7,926,646 entitled Double-Sealed, Bearingless, Reciprocating Conveyor with Slat Supporting Guide Trough Subdecks, U.S. Pat. No. 8,616,365 entitled Double-Sealed, Bearingless, Reciprocating Conveyor with Slat Supporting Guide Trough Subdecks, U.S. Pat. No. 6,651,806 entitled Sealless Slat Type Reciprocating Conveyor, and U.S. Patent Application Publication 2014/0090960 entitled Bearingless Reciprocating Slat-Type Conveyor Assemblies.
The following descriptions of patents are meant to describe known systems.
U.S. Pat. No. 3,530,895 to Rothrock (the “Rothrock reference”) directed to an automatic fluid pressure switching valve. Described as a hollow switching valve body houses a hollow sleeve freely reciprocative therein, and a control stem extends slidably through the body and sleeve. A pair of spaced conductor grooves in the sleeve cooperates with an inlet port, a pair of outlet ports and an exhaust port in the body to deliver fluid under pressure from the inlet port selectively to the pair of outlet ports and exhaust port. A by-pass groove in the movable control stem cooperates with a by-pass port in the sleeve between the conductor grooves to by-pass fluid under pressure from the inlet port selectively to opposite ends of the sleeve to move the latter and switch the delivery of fluid under pressure from one outlet port to the other. This reference describes a pilot spool controlled switching valve that is commonly used to control a reciprocating slat-type conveyor.
U.S. Pat. No. 3,534,875 to Hallstrom, Jr. (the “Hallstrom, Jr. reference”) describes a reciprocating conveyor and more specifically, a plurality of groups of at least three elongated slats that are arranged side by side to form a conveyor type truck bed. The slats of each group are connected to a drive mechanism in such manner that there are always a greater number of slats of each group moving simultaneously in the conveying direction while the remaining slat or slats of the group move in the opposite direction. This patent (which is assigned to and owned by the applicant of the present invention) describes a cam and follower system. The cam is rotated and the followers drive the cross beams and slats so that more of the slats are moving in the conveying direction than are retracting. This patent also mentions that hydraulic cylinders or rack and pinion gears could be used to move the slats and that the direction of conveyance can be changed by rotating the cam in the opposite direction.
U.S. Pat. No. 3,905,290 to Caughey (the “Caughey reference”) describes a self-feeding press for producing strip material. The Caughey reference describes a press for compacting and integrating material to form a continuous strip comprising spaced parallel arrays of long narrow bars, a frame supporting the bars in each array for reciprocal movement, a feeder for supplying material to the space between the arrays of bars at one end of the press, rams for effecting relative movement of the arrays of bars toward each other to apply compacting pressure, and rams for effecting longitudinal movement of the bars in each array in a predetermined succession in one direction and for retracting all of the bars in consonance in the other direction. The reciprocating slat-type conveyor described in the Caughey reference is driven by hydraulic or pneumatic rams, each ram being controlled by a four-way switching valve to control which direction it is moving. The four-way switching valves are controlled by solenoids. The solenoids are controlled by switches which are turned on and off by a rotating cam system that is driven by a hydraulic or electric motor. The Caughey reference does not describe, does not appear to contemplate, and/or does not appear to modify (without significant re-design) a system or method for reversing the direction of conveyance.
U.S. Pat. No. 4,143,760 to Hallstrom (the “Hallstrom reference”) describes a reciprocating conveyor, and, more specifically, at least one group of at least three elongated slats mounted side-by-side on a frame for longitudinal reciprocation to form a conveyor, the slats being connected to a fluid pressure drive mechanism which is operable to move all of the slats of each group from a start position simultaneously in a load-conveying direction and then to move the slats of each group sequentially in the opposite direction from the advanced position back to the start position, the slats of each group being interengaged releasably in the conveying direction to insure simultaneous movement. This patent (which is assigned to and owned by the applicant of the present invention) describes a reciprocating slat-type conveyor that is driven by hydraulic rams; the sequencing of the rams is controlled by check valves. The direction of motion (either extending or retracting) of all of the rams is controlled by a four-way hydraulic valve (switching four-way valve). The switching four-way valve is controlled by a pilot four-way valve that is moved back and forth by the motion of the cross beams that the slats are attached to. This pilot valve functions to latch the switching four-way valve in one or the other of two positions. The direction of conveyance is changed by a separate, hand controlled, hydraulic valve which either bypasses the check valves or does not bypass them (see the description for details).
U.S. Pat. No. 4,793,468 to Hamilton et al. (the “Hamilton reference”) directed to a multiphase sliding floor for continuous material movement. The Hamilton reference further describes the invention as an apparatus, and a related method, for controlling a moving floor having multiple sliding slats, to produce a practically continuous load-moving force on a load carried on the apparatus. The slats are reciprocated back and forth by hydraulic cylinders, each of which controls a group of slats that are moved together. At any given time, a majority of slats are moving together in the desired direction, and carry a load in this direction at a nearly uniform velocity. The remainder of the slats is moved in a reverse direction, but at a speed that is a multiple of the forward speed of the majority of the slats. Each group of slats is moved through a forward stroke at a relatively low speed; then through a backward stroke at a higher speed. This reference discusses the use of magnets for triggers for a proximity switch to sense the positions of the slats to set the timing of the slat motion. This reference also discusses using a linear sensor to actually sense the position of the slats for more precise control. This reference further discusses the use of a computer processor to control the sequencing of the slats. The exiting oil from the slowly moving cylinders is routed through the one cylinder that is retracting making it go faster. The controller switches the valves at the appropriate times for proper operation of the system (see paragraph beginning at column 4, line 8). Change of conveyance direction is accomplished by changing how the switching valve of each cylinder is switched (see paragraph beginning at column 8, line 34). Each cylinder has its own three- or four-way valve. The annulus (ring-shaped) end(s) (of all of the cylinders) are joined.
U.S. Pat. No. 4,969,387 to Foster (the “'387 reference”) is directed to a hydraulic drive unit with single piston rod and plural cylinder bodies. The hydraulic drive unit contains a plurality of piston heads (P1, P2, P3) that are spaced apart along the length of a single piston rod (R). A separate traveling cylinder body (CB1, CB2, CB3) is associated with each piston head (P1, P2, P3). The traveling cylinder bodies (CB1, CB2, CB3) and the piston heads (P1, P2, P3) define first fluid chambers (1A, 2A, 3A) on a common side of the piston heads (P1, P3, P3) and a set of second fluid chambers (1B, 2B, 3B) on a common opposite side of the piston heads (P1, P2, P3). A separate fluid supply and return passageway is provided within the piston rod (R) for each of the working chambers (1A, 1B, 2A, 2B, 3A, 3B). Center members (C1, C2, C3) are secured within the hollow interior of the piston rod (R) and serve to divide the hollow interior into four axial sections (122, 124, 126, 128). The piston rod (R) includes first and second end members (RE1, RE2). The first end member (RE1) includes outer end ports (P1A, P1B, P2A) for the fluid delivery and return passageways for three of the working chambers (1A, 1B, 2A). End member (RE2) includes outer end ports (P2B, P3A, P3B) for the fluid delivery and return passageways for the remaining three working chambers (2B, 3A, 3B). The fluid delivery and return passageways are defined in part by concentric tubes (118, 120, 70, 66) located within piston rod (R) and the inner spaces (122, 124, 126, 128). The control system for transmitting fluid pressure to and from the working chambers (1A, 1B, 2A, 2B, 3A, 3B) includes sequencing valves which are separate units from the piston rod (R), the piston heads (P1, P2, P3) and the cylinder bodies (CB1, CB2, CB3). The sequencing valves are positioned to control the delivery of pressure fluid into the working chambers (1A, 1B, 2A, 2B, 3A, 3B). The '387 reference, therefore, describes the cylinders that are working off of one common shaft instead of each cylinder having its own.
U.S. Pat. No. 5,103,866 to Foster (the “'866 reference”) describes a poppet valve and valve assemblies utilizing the same and, more specifically, in a housing, there is formed, in series, a first end cavity, a first cylinder cavity, a pressure cavity, a second cylinder cavity and a second end cavity. The cavities are separated by walls which include orifices. Two identical valve members are located in the housing. The first valve member has a piston and a valve plug in the first end cavity and a valve plug in the pressure cavity. The second valve member has a piston and a valve plug in the second end cavity and a valve plug in the pressure cavity. Pressure in the pressure cavity acts on the confronting ends of the two valve members. A two position control rod, in a first position, connects pressure to the piston in the first end chamber and connects the second end chamber to return. The piston has a larger area than the second end of the valve member, creating a force differential which moves the first valve member endwise inwardly. Pressure acting on the second end of the second valve member moves it endwise outwardly. The same control rod, in its second position, connects the second piston with pressure and the first piston with return. Pressure acting on the second end of the first valve member moves it endwise outwardly. Pressure acting on the second piston moves the second valve member endwise inwardly. Such movement of the valve members moves the valve plugs to open and close orifices in the separator walls, to switch pressure and return between two paths leading from the valve assembly. This reference describes a typical switching valve used on reciprocating slat-type conveyors for switching the hydraulic fluid direction. The '866 reference does not describe any way to isolate the cylinders from the hydraulic supply to turn the system off.
U.S. Pat. No. 5,193,661 to Foster (the “'661 reference”) describes a system of linear hydraulic motors and further, that the piston rods (10, 12, 14) of three linear hydraulic motors (M1, M2, M3) are stationary and include fluid pressure passageways (40, 52, 42, 54, 44, 56) which direct fluid pressure into and out from working chambers (16, 34, 18, 36, 20, 38) on opposite sides of piston heads (22, 24, 26). Movable cylinder barrels (16, 18, 20) are connected to a load, e.g. floor members (FM1, FM2, FM3) of a reciprocating floor conveyor (FIG. 18). The outer ends of the piston rods (10, 12, 14) include balls and the balls include ports (46, 58, 48, 60, 50, 62) through which fluid pressure is delivered or removed. Associated with each port is a limit valve LV1, LV2, LV3, LV4, LV5, LV6. Limit valves (LV1, LV2, LV3) are pushed into an open position by a retraction of the motors (M1, M2, M3). Limit valves (LV4, LV5, LV6) are pulled into an open position by extension of motors (M1, M2, M3). The limit valves (LV1, LV2, LV3, LV4, LV5, LV6) includes springs biasing them into closed positions. The push and pull forces are in a direction opposite this spring force. Limit valves (LV1, LV2, LV3, LV4, LV5, LV6) are also opened by line pressure when flow is in a direction opposing the spring force. The system includes a two position switching valve (SV) controlled by a two position pilot valve (PV). The system operates to move the motors (M1, M2, M3) in unison, in a first direction, and to retract them sequentially. The system is reversible. This reference describes a control system that uses pilot operated check valves to bypass or enable the sequencing poppets of the hydraulic cylinders to change the direction of conveyance. This reference also describes a switching valve that is controlled by a separate pilot spool. The switching valve is a system of poppets. U.S. Pat. No. 5,315,916 to Foster (the “'916 reference”) and U.S. Pat. No. 5,427,229 to Foster (the “'229 reference”) are similar to the '661 reference.